Process for the purification of triphenylmethane compounds and pressure sensitive copysheet containing same

ABSTRACT

Triphenylmethane dyes are obtained in a purified or more concentrated condition which eliminates the excess aromatic amines and by-products obtained during the synthesis of the triphenylmethane dyes. These purified triphenylmethane dyes show special utility when used in combination with an electron acceptor (Lewis acid) to produce carbonless copy paper or when used as reactants in the manufacture of other dyes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of prior copendingapplication Ser. No. 328,899 filed Dec. 9, 1981, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for purifying triphenylmethanecompounds which are essentially water insoluble and which contain anaromatic primary amine as an impurity therein. This invention alsorelates to carbonless copy paper incorporating purified dye precursors,especially those which have been purified by the process of thisinvention.

2. Description of the Prior Art

Recording sheets of the type which undergo a change in color from acolorless state to a colored state by pressure have long been known aspressure-sensitive or chemical carbonless copy paper (e.g. as disclosedin U.S. Pat. Nos. 2,711,375; 2,712,507; 2,730,456; 2,730,457; 3,418,250;3,432,327; 3,955,025; 4,226,442; etc.). The use of electron donor dyeprecursors such as Crystal Violet Lactone and Michler's Hydrolparatoluene sulfinate in carbonless copy systems is also known in theart. None of the prior art teaching, however, discloses the use of thepurified triphenylmethane compound of this invention as a dye precursorin pressure-sensitive copy paper.

The manufacture of water-insoluble triphenylmethane dyes can beaccomplished by methods well known in the art, such as thoserepresentatively taught in U.S. Pat. Nos. 3,671,553 and 3,925,094.Therefore, the triphenylmethane dye precursors taught herein can bemanufactured, for example, by the following representative methods:

1. By the reaction of rosanilines with primary aromatic amines in thepresence of acid catalysts (especially benzoic acid), wherein an aminesolution of the color bases is directly obtained (cf. Fierz-David,Kunstl. organische Farbstoffe 1926, page 262 and BIOS Final Report 1433,page 30 et seq.);

2. By the conversion of amine solutions of the colorbase-tetrachloroaluminates, which can be obtained according to GermanPat. Nos. 1,098,652, 1,161,370 and 1,161,371 or Belgian Pat. No.718,410, by reacting 4,4',4"-trichlorotrityl or4,4'-dichlorotrityl-tetrachloroaluminates with primary aromatic amines,by means of aqueous alkali metal hydroxide solution into the aminesolution of the free color bases. This produces the triphenylmethanecompound as a solution in the remaining excess amine;

3. By the reaction of diphenyl amines with aromatic carboxylic acids ortheir functional derivatives (for example, benzotrihalides, anhydridesor acid halides) in the presence of acid catalysts and subsequenttreatment with an aqueous alkali metal hydroxide, whereupon solutions ofthe color bases are obtained in the aromatic amine used in excess.

Typically, these dyes are utilized as the amine solution since theexcess amine acts as a convenient solvent for the triphenylmethaneproduct. There are difficulties inherent in the use of these impurematerials, however. First, the intermediates and by-products formedduring the manufacture of these compounds, as well as the aromaticamine, remain in the end product and thus reduce its tinctorialstrength. Second, the aromatic amine which remains with the dye mayconstitute a health hazard due to its toxic nature. Third, the yield ofproducts derived from the use of the triarylmethane compounds asreactants (e.g. to produce the monosulfonation products) is reduced dueto the presence of the impurities. Fourth, surprisingly, it has now beenfound that the impurities and reaction by-products derived during thesynthesis of these triphenylmethane compounds impart a characteristicwhich causes "blushing" or premature color development when unpurifieddye precursors are utilized in carbonless copy paper.

No completely satisfactory method of purification yielding the dye inits carbinol form has been described in the prior art. Thetriphenylmethane compounds involved in this invention are essentiallyinsoluble in aqueous media in both their carbinol and salt forms. Assuch, one cannot purify the products to remove the unreacted amine andother impurities by slurrying the salt form of the dye in the presenceof aqueous caustic and heating to obtain the 100% carbinol form. Thatobvious route does not go in high yield probably due to the formation ofa layer of the insoluble carbinol form of the dye on the surface of theamorphous salt which prevents further reaction. U.S. Pat. No. 3,679,713teaches a method of purifying water-soluble basic triphenylmethane dyes,but does not specifically teach a process for those triphenylmethanedyes which are water insoluble in both their salt and carbinol form.This patent teaches purification by mixing the water-soluble salt of thedye with a water immiscible solvent and an inorganic base to produce asolvent solution of the color base from which the purified salt can beextracted or precipitated after reacting the color base with an acid.

U.S. Pat. No. 3,652,602 teaches a method of purification which involvesseparation of the mineral acid salts of the dyes, followed by generationof the carbinol bases by reaction with aqueous alkali hydroxide in anexcess of aromatic amine. The aromatic amine can then be distilled offto produce the carbinol base. This process is not totally effective, andit has proven impossible to remove all of the aromatic amine unless suchstringent conditions are used which result in partial degradation of thedesired carbinol base product.

U.S. Pat. No. 3,671,553 teaches purification of triphenylmethane dyes bytreating the amine solution of the dye with excess aqueous sulfuric acid(optionally in the presence of a solvent), filtering the suspension, anddistilling off water azeotropically to isolate the color base sulfate.

This invention overcomes the limitations of the prior art by removingthe carbinol form of the triphenylmethane dye from the surface of thesalt form by subjecting the carbinol form of the dye to temperatureshigher than about 100° C. under increased pressure so that the carbinolform of the dye can "melt" off the surface of the salt, oralternatively, by generating the carbinol form of the dye in thepresence of an organic solvent which is capable of dissolving the dye inits carbinol form.

The triarylmethane or triphenylmethane dyes purified by this inventionhave special utility when used as reactants for the production of otherdyes (e.g. by monosulfonation) or when used as dye precursors incarbonless copy paper.

SUMMARY OF THE INVENTION

This invention relates to pressure-sensitive carbonless copy media. Inparticular, in pressure-sensitive carbonless copy media having a firstsheet in contiguous interfacial relation with a second sheet whereinsaid first sheet comprises a planar sheet material having coated thereona substantially colorless dye precursor which is encapsulated ordispersed in a pressure-sensitive coating and wherein said second sheetcomprises a planar sheet material having coated thereon an electronaccepting material whereby the application of pressure effects a ruptureof the capsular elements or coating in the area of applied pressure toeffect a co-reacting and color-producing relationship between the dyeprecursor and the electron accepting material, the improvement whichcomprises utilizing as a dye precursor a purified triphenylmethanecompound in its carbinol form wherein said dye precursor coating issubstantially free of unreacted aromatic amine and other impurities andwherein said compound in its carbinol form has the following generalstructural formula: ##STR1## wherein R₁, R₂ and R₃ are direct linkages,phenyl, or napthyl groups; R₄ is hydrogen or methyl; X₁, X₂ and X₃ arehydrogen, halogen, alkyl of 1 to 4 carbons or alkoxy of 1 to 4 carbons;provided that at least one of R₁, R₂ and R₃ is not a direct linkage andprovided that X₁, X₂ or X₃ is hydrogen when the corresponding R₁, R₂ orR₃ is a direct linkage.

Furthermore, this invention relates to a novel process for removingaromatic amines and other contaminants from crude triphenylmethanecompounds which comprises:

(1) Heating a crude triphenylmethane compound in its carbinol form inthe presence of aqueous acid at an effective temperature to form theacid salt; and

(2) Separating the salt from the aqueous acid solution; and

(3) Washing the salt with water to remove water-soluble impurities; and

(4) Heating the salt in the presence of an aqueous base at temperaturesabove about 100° C. and at pressures above atmospheric to produce thetriphenylmethane compound in its carbinol form; and

(5) Separating the purified triphenylmethane compound in its carbinolform from the aqueous base solution.

The crude triphenylmethane compounds can also be purified by a processwhich comprises:

(1) Heating the crude triphenylmethane compound in its carbinol form inthe presence of aqueous acid at an effective temperature to form theacid salt; and

(2) Separating the salt from the aqueous acid solution; and

(3) Washing the salt with water to remove water-soluble impurities; and

(4) Heating the salt at an effective temperature in the presence of anaqueous base and an effective amount of an organic solvent capable ofdissolving the triphenylmethane compound in its carbinol form therebyproducing a solvent solution of the purified triphenyl methane compoundin its carbinol form; and

(5) Separating the solution of the purified triphenylmethane compound inits carbinol form from the aqueous base solution.

The purified products of this invention will typically contain less thanabout 0.1% aromatic amine. It is an object of this invention to providea process for the purification of triphenylmethane compounds which areessentially water insoluble in both their salt and carbinol forms. It isan object of this invention to provide a process for the purification ofcrude triphenylmethane compounds. More particularly, it is an object ofthis invention to provide a process for removing contaminants includingaromatic amines from crude triphenylmethane compounds. It is a furtherobject of this invention to prepare a dye precursor especially suitedfor use in pressure-sensitive copy paper. These and other objects ofthis invention will be apparent from the following description.

As used herein, the term "triphenylmethane compound" refers to thewater-insoluble compounds of the following general formula: ##STR2## orits corresponding water-insoluble Salt Form (representatively displayedin one of its resonance structures): ##STR3## wherein R₁, R₂ and R₃ aredirect linkages, phenyl, or napthyl groups; R₄ is hydrogen or methyl;X₁, X₂ and X₃ are hydrogen, halogen, alkyl of 1 to 4 carbons or alkoxyof 1 to 4 carbons; and Z is an anion obtained by removing a hydrogenatom from an organic or inorganic acid; provided that at least one ofR₁, R₂ and R₃ is not a direct linkage and provided that X₁, X₂ or X₃ ishydrogen when the corresponding R₁, R₂ or R₃ is a direct linkage.

As used herein, the term "crude triphenylmethane compounds" refers totriphenylmethane compounds having the structure defined above and whichare prepared by any conventional means involving reaction with anaromatic amine and wherein the excess aromatic amine remains as a"solvent" or an impurity in the dye product. The crude triphenylmethanecompounds will often also contain by-products and other impurities as aresult of their synthesis.

Although many of the uses for these triphenylmethane compounds, such astheir use as dyestuffs or as precursors for other dyes and pigments, isnot seriously affected by the presence of the excess aromatic amine,there are occasions when it would be preferred to use the pure compoundfree from contamination by the aromatic amine or other impurities. Theinvention described herein teaches a procedure for eliminating theexcess amine and the other impurities. Surprisingly, it has been foundthat the impurities and reaction by-products derived during thesynthesis of the triphenylmethane compounds impart a characteristicwhich causes "blushing" or premature color development when crudetriphenylmethane compounds are utilized in carbonless copy paper. Thepurification processes taught herein eliminates these impurities andeliminates the problem of blushing. Without this purification thetriphenylmethane compounds would not be as useful in carbonless copysystems as dye precursors. The removal of the excess aromatic aminesalso minimizes any health risk to a user of the purified product.

One of the typical methods of preparing the triphenylmethane compoundsinvolves heating pararosaniline or rosaniline and an excess of anaromatic primary amine in the presence of acid. This process invariablyleaves some impurities such as the acid and the aromatic primary amineand a small amount of by-products. The most common aromatic amines whichare used in the production of the rosaniline and pararosaniline basedtriphenylmethane compounds are aniline, the toluidines, xylidines,halogenoanilines and halogenotoluidines and napthylamines.

The compound of the most commercial importance for the production ofcarbonless copy paper appears to be the reaction product ofpararosaniline in an excess of aniline to produce thetris(4-anilinophenyl)-carbinol or its corresponding salt (for example,the hydrochloric acid salt tris(4-anilinophenyl)-carbenium chloride).

The chemistry involved in the use of these dye precursors is shownrepresentatively for tris(4-anilinophenyl)-carbinol and its chloridesalt tris(4-anilinophenyl)-carbenium chloride: ##STR4##

The triphenylmethane compounds containing an aromatic amine as animpurity therein have long been known in the prior art, and the exactmethod of their manufacture is not a critical element of this invention.The process taught herein for purifying the triphenylmethane compoundscan be used on any of these materials derived by conventional means andwhich contain an aromatic amine, usually a primary amine, as an impurityor a solvent therein.

DETAILED DESCRIPTION OF THE INVENTION

The purified triphenylmethane compounds of this invention can beprepared by a process which utilizes a solvent to dissolve the carbinoltriphenylmethane compound as it's formed, or by a process which involvesgenerating the carbinol form of the triphenylmethane compound at atemperature which is high enough to melt the carbinol triphenylmethanecompound.

The initial steps of the process for removing the aromatic amines andother contaminants from the crude triphenylmethane compound involveheating the crude triphenylmethane compound in its carbinol form in thepresence of aqueous acid at an effective temperature to form the acidsalt and then separating the salt from the aqueous solution. It ispreferred to allow the solution to cool slowly before separating thesalt to ensure the best yield of product.

The acid should be present in an amount of at least about 0.8equivalents of acid for each equivalent of triphenylmethane compound inits carbinol form. The preferred range is from about 1.0 to about 3.0equivalents acid for each equivalent of triphenylmethane compound in itscarbinol form, and especially preferred is about 1.2 to about 1.5equivalents of acid for each equivalent of triphenylmethane in itscarbinol form.

Any aqueous acid could be used to generate the salt, however due totheir low cost and effectiveness, mineral acids are especially preferredin the practice of this invention. In particular, hydrochloric acid,sulfuric acid and nitric acid have shown special utility.

Effective temperatures for forming the acid salt generally range fromabout 75° C. up to reflux temperatures. Reflux temperatures areespecially preferred.

Since the salt is essentially water insoluble, it can be separated fromthe aqueous solution by a variety of separatory techniques well known inthe art, such as decantation, or, preferably, by filtering the solidsalt product from the aqueous acid solution, and washing the presscakewith water to remove the water-soluble impurities. The presscake can beused as is or dried.

The triphenylmethane salt is useless as a dye precursor in carbonlesscopy paper since it must be converted back to the carbinol form to haveutility for this use. The salt cannot be merely heated in the presenceof aqueous base to regenerate the carbinol form of the triphenylmethanecompound, apparently because an insoluble layer of the carbinol formforms on the surface of the salt agglomerations thereby preventingfurther reaction.

In one of its aspects, this invention overcomes that drawback by heatingthe salt at an effective temperature of about 75° C. or higher in thepresence of an aqueous base and an effective amount of an organicsolvent capable of dissolving the triphenylmethane compound in itscarbinol form and then subsequently separating the solution of thetriphenylmethane compound in its carbinol form from the aqueous base.

The aqueous base should be present at a level of at least about 0.8equivalents of base for each equivalent of salt. Especially preferred isa range of about 1.2 to about 3 equivalents of base for each equivalentof salt. It is especially preferred to heat the reaction mixture toreflux temperatures. Aqueous bases which are especially useful in thepractice of this invention are the alkali metal hydroxides, andespecially sodium hydroxide and potassium hydroxide.

As used herein, the term "organic solvent capable of dissolving atriphenylmethane compound in its carbinol form" means those chemicallyneutral or basic solvents which are stable in aqueous base at thereaction temperatures of 75° C. or higher and which are capable ofdissolving at least about 1 part of carbinol triphenylmethane compoundand preferably at least 10 parts in 100 parts of solvent at atemperature of 75° C.

Effective amounts of these solvents are those amounts necessary tosolubilize the carbinol triphenylmethane formed, thereby ensuringsubstantially complete reaction of the acid salt and the aqueous base.Typically, these effective amounts will be at least 0.1 parts by weightsolvent for each part by weight acid salt. The amount of solvent couldrange up to about 30 parts by weight or more for every part by weightsalt. Especially preferred is a range of about 1 to 20 parts by weightsolvent for every part by weight of salt.

The organic solvents useful in the practice of this invention include asrepresentative examples hydrocarbons, ketones, amines, and esters. It ispreferred that the organic solvent have low polarity because highpolarity solvents can lead to premature color development.

Useful hydrocarbons include the aromatics such as benzene, toluene,xylene, ethyl benzene and the like.

Useful ketones include methyl n-propyl ketone, methyl isopropyl ketone,methyl isobutyl ketone, methyl isoamyl ketone, ethyl amyl ketone,cyclohexanone, isophorone and the like.

Useful amines include amines other than aromatic amines where the aminegroup is attached directly to the aromatic ring. Preferred aminesinclude the primary amines such as ethylenediamine, tetramethylenediamine, benzylamine, 2-ethyl-n-butylamine, and the like; secondaryamines such as piperidine, piperazine, 2-(N-methylamino)heptone and thelike; tertiary amines such as triethylamine, triisopropyl amine and thelike; heterocyclic aromatic amines such as pyridine, pyrimidine,quinoline, pyrols, etc. Also useful are the primary, secondary andtertiary amines having long chain alkyl groups derived from fatty acids.Representative examples of these amines are marketed by Armak ChemicalsDivision under the trademark ARMEEN.

Especially preferred of all the solvents are the aromatic hydrocarbonsand pyridine.

The triphenylmethane compound in its carbinol form can be convenientlyseparated from the aqueous base merely by separating the solventsolution from the aqueous phase by decantation, filtration or otherseparatory technique if the solvent is insoluble in water, or if thesolvent is water soluble by extraction of the carbinol triphenylmethanecompound into a water-insoluble solvent or alternatively by evaporatingthe solution to dryness. Once the solvent solution of triphenylmethanecompound in its carbinol form is obtained, it can be used as is or itcan be evaporated to dryness (by well-known techniques such as vacuum orsteam distillation) leaving the purified solid triphenylmethane compoundin its carbinol form.

The purification process of this invention is especially preferred forthe purification of tris(4-anilinophenyl)-carbinol, as this compoundshows excellent commercial utility in carbonless copy paper.

An alternative method for removing the carbinol form of thetriphenylmethane compound from the surface of the crystals of the saltis to maintain the temperature while heating the salt in the presence ofan aqueous base at temperatures above about 100° C. and at pressuresabove atmospheric. At this temperature range the triphenylmethane in itscarbinol form will melt off of the surface of the salt and it is notnecessary to utilize a solvent to drive the reaction to completion. Itis preferred to maintain this temperature between 100° and 200° C. andit is especially preferred to maintain it between about 100° and 165° C.The pressure should be maintained at levels above atmospheric pressureto prevent the evaporation of the aqueous solution. The preferred rangeof pressures is from about atmospheric pressure up to about 150 psi orhigher. The aqueous base should be present in the same range definedearlier.

Once the reaction of the salt and aqueous base at these temperatures andpressures is completed, the carbinol form of the triphenylmethanecompound can be separated from the aqueous solution by filtration or byany conventional means such as extraction into a solvent.

In any of the variations of this invention, the methods of separationare not critical to the practice of this invention and any conventionalseparatory technique can be utilized.

The purified triphenylmethane compound of this invention show specialutility in carbonless copy paper. Crude triphenylmethane compounds arenot acceptable for this use because they show premature colordevelopment and blushing and are especially sensitive to heat and highhumidity. These problems are apparently related to unreacted startingmaterials, impurities, and by-products formed during the manufacture ofthe crude triphenylmethane compound. Furthermore, for health and safetyreasons it is desirable to minimize exposure to aromatic amines. Use ofthe purified triphenylmethane compounds of this invention eliminates allof these problems in carbonless copy paper.

Pressure sensitive or so called "chemical carbonless" copy systemsbroadly comprise a substrate supported coating that contains a firstnormally inactive chemical reagent material that is selectivelytransferrable in response to applied pressure into a reaction providingand color producing relationship with a second normally inactivechemical reagent material contained within or comprising a secondcoating disposed on the surface of an interfacially contiguous secondsubstrate. Conventionally illustrative of such chemical typereproduction systems are transfer and duplicating systems wherein therear surface on one paper sheet substrate is provided with a coating andwhich sheet is then termed a "CB" (i.e. coated back) sheet and the frontside of that same and/or separate paper sheet substrate is provided witha coating which is then termed a "CFB" (i.e. coated front and back) or"CF" (i.e. coated front) sheet, respectively. When the coatings on a CBand a CF sheet are placed in interfacially contiguous relation andsubjected to selectively applied pressure, as by the pressure of astylus or the impact of a typewriter key on the obverse surface of theCB sheet, the operative and usually colorless chemical reagents in suchcoatings are brought into co-reactive relationship, as for example onthe surface of the CF sheet, to produce a colored image conforming tothe contour of the selectively applied pressure member.

In the system at hand, one of the normally inactive chemical reagentmaterials would be the purified triphenylmethane compound in itscarbinol form, and the other normally inactive chemical reagent materialwould be an electron accepting material. U.S. Pat. Nos. 2,712,507;2,730,456; and 3,455,721 illustratively disclose the use of encapsulateddye precursor materials in the CB coating and electron acceptingmaterials as the chromagenic reagent in the CF coating. U.S. Pat. Nos.3,787,325 and 3,894,168 illustratively disclose the disposition of thedye precursor material in the CF coating and the encapsulated electronaccepting material in the CB coating.

For the purpose of this invention, the term "electron acceptingmaterial" means any acidic material within the definition of a Lewisacid. The electron accepting material can be a polymer, a pigment, orother materials well known in the chemical carbonless copy paper art.

Acidic organic polymeric materials known in the art, which are usefulfor developing the color of the purified triphenylmethane compound inthis invention include phenolic polymers, phenol-formaldehyde polymers,acrylic polymers containing free carboxylic acids, phenol acetylenepolymers, maleic acid-rosin resins, partially or wholly hydrolyzedstyrene-maleic anhydride copolymers and ethylene-maleic anhydridecopolymers, carboxy polymethylene and wholly or partially hydrolyzedvinylmethylethermaleic anhydride copolymers and mixtures thereof.

More specifically, phenolic polymers found useful include alkyl-phenolacetylene resins, "novolacs" (a type of phenolformaldehyde polymericmaterial), and resol resins.

Illustrative examples of electron accepting pigments and materials whichare useful in the practice of this invention include the acid claylikematerials such as acid clays, active clays, attapulgite, or zeolitematerials such as sodium aluminum silicate materials or such in whichthe sodium has been exchanged for hydrogen or some other metal ion asdisclosed in U.S. Pat. Nos. 2,581,186 and 2,641,557.

Other solid materials which are useful as the electron acceptingmaterial include organic acids such as aromatic carboxy compounds (e.g.salicylic acid, etc.), organic hydroxy compounds (e.g. p-t-butylphenol,p-t-amylphenol, o-chlorophenol, m-chlorophenol, p-chlorophenol, andmetal salts thereof (e.g., the zinc salt, etc.). Suitable colordevelopers are described also in U.S. Pat. Nos. 2,501,331; 3,669,711;3,427,180; 3,455,721; 3,516,845; 3,634,121; 3,672,935; 3,732,120 as wellas elsewhere in the patent and technical literature.

Other Lewis acids such as zinc chloride can be encapsulated as a solidor as an aqueous solution in wax, or other pressure-sensitive capsulesas the electron accepting material. Representative uses of zinc chloridein this manner include those taught in Belgian Pat. Nos. 874,481, and877,832; Ger. Offen. No. 2,809,657; Fr. Demande No. 2,462,271 and JapanKokai Tokkyo Koho No. 80 69,494.

Either the dye precursor or the electron accepting material can be, ifdesired, encapsulated in pressure sensitive capsules or can be dispersedin a coating, or in the case of the electron accepting material, couldbe the coating itself. The encapsulation technique is well known in theart and can be performed by the procedures described, for example, inU.S. Pat. Nos. 2,712,507; 2,730,457, 2,800,457, 2,800,458; (reissued asU.S. Pat. No. Re 24,899) and U.S. Pat. No. 3,041,289. Preferred examplesof eligible capsule wall materials include gelatin, gum arabic,agar-agar and many others thoroughly described in the aforementionedpatents.

The dye precursors could also be dispersed in a pressure sensitivehydrophobic binder material. The hydrophobic resins includepolyvinylbutyral, polyvinylacetal, and polyvinylformal resins. Morespecifically, suitable polyvinylbutyrals comprise the Butvarpolyvinylbutyral resins which are manufactured by Monsanto Polymers andPetrochemicals Company and a preferred resin is Butvar B-98. Such ButvarB-98 have an average molecular weight of about 30,000 to 34,000; ahydroxyl content, expressed as percent polyvinyl alcohol, of 18 to 20;an acetate content, expressed as percent polyvinylacetate, of 0 to 2.5;and a butyral content, expressed as percent polyvinylbutyral, of about80.

As used herein, the term "encapsulated dye precursor" is intended toinclude a dye precursor which is encapsulated in pressure-sensitivecapsules or a dye precursor which is dispersed in a pressure-sensitivebinder material.

If desired, the purified triphenylmethane dye precursor can be utilizedin combination with additional dyes and/or pigments.

Pigments which have special utility as opacifier-fillers include thewater-insoluble and approximately chemically neutral pigments such ascalcium carbonate, barium sulfate, titanium dioxide, magnesiumcarbonate, and other materials known in the art. It is preferred thatthe approximately chemically neutral pigments be slightly basic ratherthan slightly acidic because acidic pigments tend to develop the colorof the dye precursor materials prior to use.

Additional dyes which are reactive with the electron acceptor materialsand which could be used in combination with the purifiedtriphenylmethane compounds taught in this invention include the othertriarylmethane compounds, as well as the diarylmethane compounds,xanthene compounds, thiazine compounds, spiropyran compounds, and othermaterials well known in the art. Specific examples of color formerswhich are suitable include, the triphenylmethane compounds such as3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, i.e., crystalviolet lactone, 3,3-bis-(p-dimethylaminophenyl)phthalide,3-(p-dimethylaminophenyl)-phthalide,3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)-phthalide,3-(p-dimethylaminophenyl)-3-(2-phenylindol-3-yl)-phthalide,3,3-bis-(1,2-dimethylindol-3-yl)-6-dimethylainophthalide,3,3-bis-(1,2-dimethylindol-3-yl)-6-dimethylaminophthalide,3,3-bis-(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide,3,3-bis-(2-phenylindol-3-yl)-5-dimethylaminophthalide,3-p-dimethylaminophenyl-3-(1-methylpyrrol-2-yl)-6-dimethylaminophthalide,etc.

Illustrative diphenylmethane compounds are4,4'-bis-dimethylaminobenzhydrin benzyl ether,N-halophenylleucoauramine, N-2,4,5-trichlorophenyl-leucoauramine, etc.

Examples of xanthene compounds are rhodamine-B-anilinolactam,rhodamine-(p-nitroanilino)lactam, rhodamine-B-(p-chloroanilino)-lactam,7-dimethylamino-2-methoxyfluoran, 7-diethylamino-2-methoxyfluoran,7-diethylamino-3-chloro-2-methylfluoran,7-diethylamino-3-(acetylmethylamino)fluoran,7-diethylamino-3-(dibenzylamino)fluoran,7-diethylamino-3-(methylbenzylamino)-fluoran,7-diethylamino-3-(chloroethylmethylamino)fluoran,7-diethylamino-3-(diethylamino)fluoran, etc..

Suitable examples of thiazine compounds are benzoylleucomethylene blue,p-nitrobenzylleucomethylene blue, etc..

Spiro compounds include 3-methyl-spiro-dinaphthopyran,3-ethyl-spiro-dinaphthopyran, 3,3'-dichlorospiro-dinaphthopyran,3-benzyl-spiro-dinaphthopyran,3-methylnaphtho(3-methoxybenzo)-spiropyran,3-propyl-spiro-dibenzodipyran, etc..

One or more of the above-illustrated color formers can be appropriatelyselected and be used in combination with the purified triphenylmethanecompound of this invention. Use of these additional dyes in combinationwith the purified carbinol form of the triphenylmethane compound enablesthe formulator to produce dyes of various colors. For example, thecombination of about 36.5% tris(4-anilinophenyl)-carbinol, 40.5% BasicYellow 37 and 13.0% Basic Red 14 produces an excellent, opaque blackdye.

Suitable supports which can be used in the practice of this inventioninclude plastic films, paper, resin-coated paper, synthetic papers, andthe like.

The following examples are intended to illustrate the invention, but arenot presented as limitations upon the scope of the claims. As used inthese examples the crude triphenylmethane compound was preparedaccording to the general method described in Kunstl. organisheFarbstoffe 1926, page 262 and BIOS Final Report 1433, page 30 et seq.and involved the reaction of pararosaniline and excess aniline in thepresence of benzoic acid catalyst to produce an aniline solution oftris(4-anilinophenyl)-carbinol as the crude triphenylmethane compound.

EXAMPLE 1

A five liter, 3 neck flask is fitted with a stirrer, reflux condenser,and a heating mantle. The flask was charged with 3,500 milliliterswater, 400 grams crude carbinol triphenylmethane compound and 70milliliters concentrated reagent hydrochloric acid (83.3 grams 36% HCL).The crude carbinol triphenylmethane compound was about 88%tris(4-anilinophenyl)-carbinol with the major contaminants beinganiline, diethylene glycol, and sodium benzoate. This mixture wasrefluxed with stirring for ten hours and then filtered without coolingthrough an 18.5 cm Buchner funnel. The filtered product was washed to atotal wash volume of 18 liters of hot water, to produce approximately522 grams of a wet cake of the chloride salt having approximately 72.0%dry content (yield was about 376 grams of product on a dry basis).

Two hundred sixty one grams of the wet filter cake (188 grams on a drybasis), 800 milliliters water, and 35 grams 50% sodium hydroxide werecharged into a five liter, three neck flask fitted with stirrer, refluxcondenser and heating mantle. The mixture was stirred, heated to refluxand held at reflux temperatures for about one hour. Eight hundredmilliliters of toluene was carefully added to the mixture. (Thisaddition must be done carefully because the reaction mixture is at atemperature of approximately 99° C. which is greater than thetemperature of the toluene-water azeotrope of 84° C. Alternatively, thebatch could be cooled to a lower temperature prior to the addition ofthe toluene.) The reaction mixture is then refluxed for an additionalsix hours. After the six-hour period an additional 2,169 milliliters oftoluene was added and the refluxing continued for two more hours. Thesplit addition of toluene is useful to insure good stirring and goodadmixture for each of the toluene additions.

The reaction mixture was then allowed to cool to room temperature andfiltered through a polypropylene 100 micron filter into a five literseparatory funnel. The water layer was discarded, and the toluene layercontaining the purified tris(4-anilinophenyl)-carbinol was analyzed by aUV spectrophotometer indicating an approximate 6% solution oftris(4-anilinophenyl)-carbinol in toluene, essentially free fromaniline, undesirable by-products and other contaminants.

This solution can be used as is, or the toluene can be removed and thedried purified carbinol product can be used.

The purified product shows special utility in carbonless copy paperformulations.

EXAMPLE 2

A three liter, three neck flask fitted with stirrer, reflux condenserand heating mantle was charged with 200 grams of the crudetriphenylmethane compound, 200 milliliters water and 35 millilitersconcentrated hydrochloric acid. The crude triphenylmethane compound wasapproximately 85% tris(4-anilinophenyl)-carbinol with the remaining 15%being aniline, sodium benzoate and lesser amounts of other impuritiesand by-products. The mixture was stirred and refluxed for approximately18 hours. The reaction mixture was filtered while still hot, and washedwith hot water until the test for chloride ion (silver nitrate solution)in the effluent was no longer positive. The product was dried at 70° C.to yield 183.3 grams of the dry, purified chloride salt.

The three liter flask equipped as described above was charged with the183.3 grams of the dry chloride salt, and 400 grams (427 milliliters)pyridine. This mixture was stirred and a solution of 35 grams 50% sodiumhydroxide in 400 milliliters of water was added. The mixture wasrefluxed and stirred for 31/2 hours and then allowed to cool overnight.After standing, the mixture was combined with 2,000 milliliters ofwater, mixed, and the aqueous layer decanted off. The remaining productwas washed by decantation with two additional 1,500 milliliter wateradditions. The mixture was washed with additional water until the masswas mostly solidified. The total water wash was approximately 12 liters.This mass was returned to the three liter, three neck flask, mixed withadditional water, and steam distilled until the pyridine odor was absentfrom the distillate. The remaining water was decanted from the productand the product dried at 50° C. The product was approximately 169.5grams of dry tris-(4-anilinophenyl)-carbinol, essentially free fromimpurities.

EXAMPLE 3

A one liter, three neck flask equipped with stirrer, reflux condenserand heating mantle was charged with 200 milliliters water, 7.8 grams 50%sodium hydroxide, and 40.0 grams of dry, purified chloride salt preparedin the manner described in Example 2 by refluxing the crudetriphenylmethane compound in aqueous mineral acid. This mixture wasstirred, heated, and maintained at reflux temperatures for one hour. Twohundred milliliters of methyl iso-butyl ketone was added and refluxedfor six more hours. An additional charge of 240 milliliters iso-butylketone was made and reflux continued for two more hours. After this timeperiod, an additional 100 milliliters methyl iso-butyl ketone was added,and the mixture was allowed to cool to room temperature. The aqueouslayer was decanted, and the methyl iso-butyl ketone layer containing thetris(4-anilinophenyl)-carbinol was washed several times with additionalwater which was then decanted. If desired, the methyl iso-butyl ketonecan be evaporated to leave a dry, solid carbinol product. The purifiedcarbinol product was an excellent dye precursor when used in carbonlesscopy systems.

EXAMPLE 4

A 500 milliliter three neck flask equipped with stirrer, refluxcondenser and heating mantle was charged with 250 milliliters water,8.75 grams 50% sodium hydroxide, 11.5 grams Armeen C (high molecularweight aliphatic coco-amine manufactured by Armour Industrial ChemicalCompany having a major component C₁₂ H₂₅ NH₂, an amine number of about267, and which is derived by conversion of the coconut fatty acidnitrile to the primary fatty amine by catalytic hydrogenation), and 47grams dry chloride salt prepared as described in Example 2 by refluxingthe crude triphenylmethane compound in aqueous hydrochloric acid. Themixture was stirred and refluxed for approximately 20 hours. The waterlayer was decanted, and the solid carbinol product was ground and thenslurried in 300 milliliters water, filtered and washed with 500milliliters water. The carbinol product was dried at 50° C. for about31/2 days. The product was tris(4-aninilinophenyl)carbinol essentiallyfree from aniline and undesirable impurities. The total yield of dryproduct was approximately 55.5 grams.

EXAMPLE 5

A pressure kettle equipped with stirrer, thermometer, and pressure gaugewas charged with 124.5 grams of the wet cake of chloride salt preparedas described in Example 1, five hundred milliliters water and 17.5 grams50% sodium hydroxide. The pressure kettle was bolted shut and heated to100° C. over about a 22 minute period. The pressure kettle wasmaintained at 100° to 110° C. for about one hour and then thetemperature was increased to 125° C. and held for an additional hour.The temperature was then increased gradually (over about a one hourperiod) to 150° C. and held there for nearly one hour. The pressureinside the kettle at this temperature was approximately 58 PSI. Thereaction mixture was then cooled to about 100° C. over a 15 minuteperiod and the kettle was opened. The product was a blackish-browntaffy-like solid. The solid product was ground with a pestle, washedrepeatedly with hot water and then dried at about 50° C. to obtain a dryproduct. The product was identified by thin layer chromatography astris(4-anilinophenyl)-carbinol essentially free from aniline andundesirable contaminants.

EXAMPLE 6

A three liter, three neck flask equipped with stirrer, reflux condenserand heating mantle was charged with 1,750 milliliters water, 38.3milliliters concentrated nitric acid (0.6 mole nitric acid) and 200grams crude triphenylmethane compound. The crude triphenylmethanecompound was approximately 85% tris(4-anilinophenyl)-carbinol,approximately 10% aniline and approximately 5% of other by-products andimpurities such as sodium benzoate. The reaction mixture was heated toreflux and maintained at that temperature for approximately 16 hours.The reaction product was filtered while still hot and washed repeatedlywith water until the wash liquors gave a neutral pH to pH paper. The 309grams of wet press cake was dried at approximately 70° C. to yieldapproximately 191.2 grams of the dry, purified nitric acid salt.Analytical evaluation indicated less than 0.1% aniline in the purifiedsalt.

The 191.2 grams of nitric acid salt, 800 milliliters of water and 35grams 50% sodium hydroxide were charged into a reaction vessel fittedwith stirrer, condenser and heating mantle. The mixture was stirred,heated to reflux and held at reflux temperatures for one hour. Eighthundred milliliters of toluene was carefully added and reflux continuedfor about six hours. An additional 2,000 milliliters of toluene wasadded and reflux continued for two additional hours.

The reaction mixture was cooled, filtered and the toluene layerseparated by decantation and evaporated to dryness to yield a pure, drysample of tris(4-anilinophenyl)-carbinol which could be used incarbonless paper formulations without premature color development orblushing.

EXAMPLE 7

This example shows the incorporation of the purified dye precursor in aCF coating. This method of producing carbonless copy paper is described,in general, in U.S. Pat. No. 4,226,442.

The coating for the CF sheet could be produced by the following recipe:

    ______________________________________                                        Raw Materials          %                                                      ______________________________________                                        Methyl Ethyl Ketone    63.28                                                  Polyvinyl Butyral      4.0                                                    Potassium Hydroxide Flakes                                                                           0.12                                                   Tamol 731 S.D. Dispersant                                                                            0.2                                                    Titanium Dioxide       5.0                                                    Calcium Carbonate      25.0                                                   Methyl Ethyl Ketone    10.0                                                   Dry tris(4-anilinophenyl)-carbinol                                                                   2.4                                                    Purified as Shown in Example 2                                                ______________________________________                                    

by the procedure of adding the methyl ethyl ketone, the polyvinylbutyralbinder material, the dispersant, and the potassium hydroxide withcontinuous agitation to dissolve such constituents in the solvent. Aftercomplete dissolution, the dry purified dye precursor is added withcontinuous stirring to dissolve the dye precursor and to obtain auniform dispersion of it in the solution. To the above liquid mixture isthen added the requisite amounts of the calcium carbonate-titaniumdioxide opacifier-fillers. This addition should be accompanied bycontinuous stirring of the constituents in the liquid vehicle to obtaina uniform dispersion of the opacifier-filler therewithin.

The CF coating formula prepared as taught in this example can be drawndown onto a paper substrate using a wire wrapped draw down bar, andallowed to dry. This coated paper makes an excellent CF sheet forcarbonless copy systems.

EXAMPLE 8

This example teaches a representative method which can be used toprepare a CB coating for carbonless copy paper. The CB coating on therear of a sheet of paper which is to be placed in intimate contact withthe CF coated paper may be of conventional character incorporating anelectron accepting acid reacting material therein, as for example, ofthe type disclosed in the patents of Hoover (U.s. Pat. No. 3,787,325)and Brockett (U.S. Pat. No. 3,894,168).

A representative CB coating can be prepared by encapsulating a 17%solution of para-phenylphenol-formaldehyde resin in xylene withpoly(vinyl alcohol) polymer film material which was made impervious byin situ treatment with resorcinol and formaldehyde as taught in BritishPat. No. 1,190,720 issued May 6, 1970 to Bayless and Emric.

Thirty-eight grams of these capsules can be mixed with 16 grams of shortalpha-cellulose floc fibers as capsule protectant material, along with120 grams of 5% aqueous poly(vinyl alcohol), "Elvanol 71-30", as bindermaterial and 112 grams of water to give a capsuler coating slurry whichmay be coated on paper. This coating can be applied to a paper substrateat about 4.5 pounds per ream to give the CB paper.

If the CF sheet of Example 7 is placed in contiguous interfacialrelation to the CB sheet of Example 8, the application of pressure willrupture the coatings in the area of applied pressure to effect a releaseof the purified dye precursor and of the electron acceptor material toproduce a distinct, blue colored image corresponding to the area of theapplied pressure. Paper prepared in this manner shows very littletendency to "blush" in high humidity or at temperatures of about 125° F.

EXAMPLE 9

This example shows a representative method of manufacturing a black dyeusing the purified dye precursors of this invention.

A one liter, three neck flask fitted with stirrer, reflux condenser andheating mantle was charged with 5.32 grams of dry, purifiedtris(4-anilinophenyl)-carbenium chloride (prepared as described in thefirst paragraph of Example 2), 120 milliliters water and 1.03 grams of a50% solution of sodium hydroxide. The mixture was stirred and heated toreflux and held at that temperature for approximately one hour. Sixtymilliliters of toluene was added to the mixture and reflux continued forapproximately six hours. An additional 160 milliliters of toluene wasadded and reflux continued for approximately one additional hour and themixture was then allowed to cool to room temperature.

To this mixture was added 3.3 grams 50% sodium hydroxide and a slurry of63 grams Basacryl Red GL (a red dye having Color Index Number 22460manufactured by BASF) in 200 milliliters water. The mixture was heatedto approximately 60° C. for about one half hour until the red colorleaves the aqueous layer and the dye is extracted up into the toluene.

To this mixture was added a solution of 1.04 grams Calcozine Green MXconcentrated crystals (Color Index Number 42000, Color Index name--BasicGreen 4; manufactured by the American Cyanamid Company) in 20milliliters water and 0.4 grams 50% sodium hydroxide. The mixture isstirred at about 60° C. until the green color leaves the aqueous layerand the green dye is extracted up into the toluene.

To this mixture was added a slurry of 1.04 grams Basic Yellow FFP (BasicYellow 37, Color Index Number 41001, sold as Calcozine Yellow FW by theAmerican Cyanamid Company) in 20 milliliters water and 0.4 grams 50%sodium hydroxide. After approximately one half hour stirring at 60° C.all of the yellow dye is extracted out of the water layer and up intothe toluene solution.

An additional 93 milliliters of toluene was added and stirringmaintained for a few minutes. The material was then filtered by gravitythrough 100 micron polyester filter cloth into a five liter separatoryfunnel. The lower aqueous layer was discarded, and the toluene layercontaining the mixture of carbinol dyestuffs was filtered through flutedpaper to produce a toluene solution of dye. The toluene was distilledaway under vacuum to yield the dry, purified black dye mixture.

This black dye can be incorporated into a CF sheet as shown in Example 7by substituting an equal weight of the dry black dye for the drytris(4-anilinophenyl)-carbinol shown in Example 7. When the CF sheet isplaced in contiguous interfacial relation to the CB sheet of Example 8,applied pressure will effect a release of the dye precursor and of theelectron acceptor material to produce a distinct black imagecorresponding to the area of the applied pressure.

While this invention has been described by a number of specificembodiments, it is obvious that other variations and modifications maybe made without departing from the spirit and scope of the invention asset forth in the appended claims.

The invention claimed is:
 1. In a pressure-sensitive carbonless copymedia having a first sheet in contiguous interfacial relation with asecond sheet wherein said first sheet comprises a planar sheet materialhaving coated thereon a substantially colorless dye precursor which isencapsulated or dispersed in a pressure-sensitive coating and whereinsaid second sheet comprises a planar sheet material having coatedthereon an electron accepting material whereby the application ofpressure effects a rupture of the capsular elements or coating in thearea of applied pressure to effect a co-reacting and color-producingrelationship between the dye precursor and the electron acceptingmaterial, the improvement which comprises utilizing as a dye precursor apurified triphenylmethane compound in its carbinol form and wherein saidcompound in its carbinol form has the following general structuralformula: ##STR5## wherein R₁, R₂ and R₃ are direct linkages, phenyl, ornapthyl groups; R₄ is hydrogen or methyl; X₁, X₂ and X₃ are hydrogen,halogen, alkyl of 1 to 4 carbons or alkoxy of 1 to 4 carbons; providedthat at least one of R₁, R₂ and R₃ is not a direct linkage and providedthat X₁, X₂ or X₃ is hydrogen when the corresponding R₁, R₂ or R₃ is adirect linkage; and wherein said dye precursor containing coating issubstantially free of unreacted aromatic amine.
 2. The pressuresensitive carbonless copy media of claim 1 further characterized in thatthe purified triphenylmethane compound was obtained from a crudetriphenylmethane compound having unreacted aromatic amine associatedtherewith as an impurity or a solvent by a purification process whichcomprises:(1) Heating the crude triphenylmethane compound in itscarbinol form in the presence of aqueous acid at an effectivetemperature to form the acid salt; and (2) Separating the salt from theaqueous acid solution; and (3) Washing the salt with water to removewater-soluble impurities; and (4) Heating the salt at an effectivetemperature in the presence of an aqueous base and an effective amountof an organic solvent capable of dissolving the triphenylmethanecompound in its carbinol form as it is formed by the reaction of thebase and the salt thereby producing a solvent solution of the purifiedtriphenylmethane compound in its carbinol form; and (5) Separating thesolution of the purified triphenylmethane compound in its carbinol formfrom the aqueous base solution.
 3. The carbonless copy media of claim 2further characterized in that the aqueous acid utilized in thepurification process is an aqueous mineral acid.
 4. The carbonless copymedia of claim 3 wherein the mineral acid utilized in the purificationprocess is hydrochloric acid.
 5. The carbonless copy media of claim 3wherein the mineral acid utilized in the purification process is nitricacid.
 6. The carbonless copy media of claim 3 wherein the mineral acidutilized in the purification process is sulfuric acid.
 7. The carbonlesscopy media of claim 2 further characterized in that the acid utilized inthe purification process is present in an amount ranging from about 0.8to about 3.0 equivalents of acid for each equivalent of triphenylmethanecompound in its carbinol form.
 8. The carbonless copy media of claim 2further characterized in that the base utilized in the purificationprocess is an alkali metal hydroxide.
 9. The carbonless copy media ofclaim 8 further characterized in that the alkali metal hydroxideutilized in the purification process is sodium hydroxide.
 10. Thecarbonless copy media of claim 8 further characterized in that thealkali metal hydroxide utilized in the purification process is potassiumhydroxide.
 11. The carbonless copy media of claim 2 furthercharacterized in that the base utilized in the purification process ispresent in an amount of at least 0.8 equivalents of base for eachequivalent of salt.
 12. The carbonless copy media of claim 2 furthercharacterized in that the base utilized in the purification process ispresent in an amount ranging from about 1.2 to about 3.0 equivalents ofbase for each equivalent of salt.
 13. The carbonless copy media of claim2 further characterized in that the solvent utilized in the purificationprocess is present in an amount ranging from about 1 to about 20 partsby weight solvent for each part salt.
 14. The carbonless copy media ofclaim 2 further characterized in that the organic solvent utilized inthe purification process is an aromatic hydrocarbon.
 15. The carbonlesscopy media of claim 14 further characterized in that the aromatichydrocarbon utilized in the purification process is toluene.
 16. Thecarbonless copy media of claim 14 further characterized in that thearomatic hydrocarbon utilized in the purification process is xylene. 17.The carbonless copy media of claim 2 further characterized in that theorganic solvent utilized in the purification process is a ketone. 18.The carbonless copy media of claim 2 further characterized in that theorganic solvent utilized in the purification process is an amine. 19.The carbonless copy media of claim 18 further characterized in that theamine is pyridine.
 20. The carbonless copy media of claim 2 furthercharacterized in that the temperature of step 1 of the purificationprocess ranges between about 75° C. and reflux.
 21. The carbonless copymedia of claim 2 further characterized in that the temperature of step 4of the purification process ranges between about 75° C. and reflux. 22.The pressure sensitive carbonless copy media of claim 1 furthercharacterized in that the purified triphenylmethane compound wasobtained from a crude triphenylmethane compound having unreactedaromatic amine associated therewith as an impurity or a solvent by apurification process which comprises:(1) Heating the crudetriphenylmethane compound in its carbinol form in the presence ofaqueous acid at an effective temperature to form the acid salt; and (2)Separating the salt from the aqueous salt solution; and (3) Washing thesalt with water to remove water-soluble impurities; and (4) Heating thesalt in the presence of an aqueous base at temperatures above about 100°C. and at pressures above atmospheric to produce the purifiedtriphenylmethane compound in its carbinol form; and (5) Separating thepurified triphenylmethane compound in its carbinol form from the aqueousbase solution.
 23. The carbonless copy media of claim 22 furthercharacterized in that the aqueous acid utilized in the purificationprocess is an aqueous mineral acid.
 24. The carbonless copy media ofclaim 23 wherein the mineral acid utilized in the purification processis hydrochloric acid.
 25. The carbonless copy media of claim 23 whereinthe mineral acid utilized in the purification process is nitric acid.26. The carbonless copy media of claim 23 wherein the mineral acidutilized in the purification process is sulfuric acid.
 27. Thecarbonless copy media of claim 22 further characterized that the acidutilized in the purification process is present in an amount rangingfrom about 0.8 to about 3.0 equivalents of acid for each equivalent oftriphenylmethane compound in its carbinol form.
 28. The carbonless copymedia of claim 22 further characterized in that the base utilized in thepurification process is an alkali metal hydroxide.
 29. The carbonlesscopy media of claim 28 further characterized in that the alkali metalhydroxide utilized in the purification process is sodium hydroxide. 30.The carbonless copy media of claim 28 further characterized in that thealkali metal hydroxide utilized in the purification process is potassiumhydroxide.
 31. The carbonless copy media of claim 22 wherein the salt isheated in the presence of an aqueous base in step 4 of the purificationprocess at temperatures ranging up to about 200° C. at pressures aboveatmospheric.
 32. The carbonless copy media of claim 22 wherein the saltis heated in the presence of an aqueous base in step 4 of thepurification process at temperatures between about 100° and 165° C. atpressures above atmospheric.
 33. The carbonless copy media of claim 22wherein the salt is heated in the presence of an aqueous base in step 4of the purification process at temperatures above 100° C. and atpressures ranging up to about 150 psi.
 34. The carbonless copy media ofclaim 22 further characterized in that the base utilized in thepurification process is present in an amount of at least 0.8 equivalentsof base for each equivalent of salt.
 35. The carbonless copy media ofclaim 22 further characterized in that the base utilized in thepurification process is present in an amount ranging from about 1.2 toabout 3.0 equivalents of base for each equivalent of salt.
 36. Thepressure-sensitive carbonless copy media of claim 1 furthercharacterized in that the dye precursor istris(4-anilinophenyl)-carbinol.